1. Field of the Invention
The present invention relates in general to a vehicle control apparatus including a drive-power-source-torque control portion for controlling a torque of a drive power source (e.g., engine) for a vehicle, and more particularly to techniques for determining a target vehicle drive torque on the basis of an operating amount of a manually operated vehicle accelerating member and a selected operating position of a transmission having respective different speed ratios, so as to permit a smooth change of the vehicle drive force with a change of the operating amount of the vehicle accelerating member, for thereby improving the drivability of the vehicle, irrespective of a shifting action of the transmission, that is, irrespective of a non-smooth change of the speed ratio of the transmission.
2. Discussion of Related Art
In a vehicle including an automatic transmission having a plurality of operating positions having respective different speed ratios, wherein a selected one of the operating positions is automatically selected, the transmission may suffer from a shock during a shifting action thereof. To reduce the shifting shock of the automatic transmission, a known vehicle is provided with an engine output control apparatus arranged to temporarily control the torque of a drive power source in the form of an engine, so as to smooth a variation in the output torque of the transmission. For example, JP-A-9-119328 discloses a technique wherein a relationship between an operating amount of a manually operated vehicle accelerating member such as an accelerator pedal and an opening angle of an electronically controlled throttle valve is temporarily changed to reduce the engine torque in the process of a shifting action of the transmission, for reducing a change of the output torque of the transmission in the process of the shifting action, to thereby minimize a shifting shock of the transmission.
JP-A-9-310627 discloses an engine output control apparatus for a vehicle, wherein an electronically controlled throttle valve is controlled by an engine control unit according to an output signal of an accelerator sensor, such that the output torque of an engine is reduced upon a shifting action of an automatic transmission, for reducing a shifting shock of the transmission.
Unlike a continuously variable transmission, an automatic transmission having a plurality of operating positions having respective different speed ratios suffers from a considerably large amount of change of its output torque before and after a shifting action thereof, due to a non-smooth abrupt change of the speed ratio from a value before the shifting action to a value after completion of the shifting action. The conventional engine output control apparatus is not satisfactory in its capability to minimize a drawback that the drivability of the vehicle tends to be deteriorated due to a considerably large amount of change of the vehicle drive force upon a shifting action of the automatic transmission.